Capping machine



E. W. DONAHUE CAPPING MACHINE Oct. 26, 1937.

Filed Feb. 1, 1935 2 Sheets-Sheet 1 lNl/ENTOR.

Oct. 26, 1937. E. w. DONAHUE CAPPING MACHINE 2 Sheets-Sheet 2 Filed Feb. 1, 1935 e3 l g 27 21 /20 2 i '26 2 @atenited Get. 26, 137

UNITED STATES CAPPIN G MACHINE Edward ,W. Donahue, Cambridge, Mass., asslgnor to The Ludcke Corporation, Water-town, Mass., a corporation oiMassachusetts Application February 1, 1935, Serial No. 4,537

6 Claims.

This invention relates to machines for applying screw caps to containers.

Prior machines of this type have usually consisted of a motor driving a flexible shaft, on the end of which was mounted a tool for engaging the cap to be tightened, afriction clutch being installed somewhere in the driving connections for the tool to limit the torque applied to it. In using such a machine the operator supports the tool in one hand and presses it down upon the tops of the caps of successive containers, holding the pressure on each cap until the tightening operation has been completed. Usually only a very few revolutions of the tool are required for this purpose, and as soon as the cap has been tightened the friction clutch slips, thus stopping the rotating movement of the tool. During the first part of the operation on any individual cap, relatively little energy is required to screw the cap on, but the flnal fraction of a revolution of the cap necessary to tighten it does take considerable effort, particularly if the cap is large in diameter. All of this effort must be supplied by the motor, and in prior machines theentire torque required for this purpose has been transmitted through the flexible shaft. This results in frequent breakage of the shafts, if a light shaft is used, and increases the efl'ort required on the part of the operator to perform the capping operation if a stiffer or heavier shaft is employed.

In applying caps of large diameter with a tool driven at a constant torque, the operator must force the tool down upon the cap with considerable pressure in order properly to tighten the cap, and at the same time he must grip the container with suflicient pressure to effectively resist the twisting action transmitted to it through the tool and the cap. Such work, therefore, rapidly tires the operator, particularly if he must keep up with the delivery of containers brought to him by a conveyor.

The present invention deals especially with the 45 problems presented by the conditions above described. It aims to improve capping machines with a view to making them more reliable, easier to operate, and better adaptable to the various requirements of the work. The invention involves both a novel structure and also a new method.

The nature of the invention will be readily understood from the following description when 55 read in connection with the accompanying drawings, andthe novel features will be particularly pointed out in the appended claims.

In the drawings, I

Figure 1 is a view, chiefly in side elevation but somewhat diagrammatic in character, of a capping machine constructed in accordance with this invention;

Fig. 2 is a vertical, sectional view through the capping tool and the parts adjacent to it;

Figs. 3 and 4 are sectional and plan views, respectively, of another form of capping tool; and

Figs. 5 and 6 are sectional and end views, respectively, of the clutch which forms one element of the organization illustrated in Fig. 1.

Referring first to Figs. 1 and 2, the machine there shown comprises a capping tool 2, a flexible shaft 3 connected with said tool, an electric motor 4 for driving said shaft, and a friction clutch 5 through which the motor is connected with the shaft.

The tool may be of any suitable form and its character necessarily will depend upon the requirements of different kinds of work.. In the particular arrangement shown, it consists of a hollow body of cylindrical form having a socket 6 in its lower face in which a cap engaging member I made of rubber or other resilient material is located. The lower side of this member has a tapered socket in it to receive the cap to be tightened.- Projecting centrally from the upper surface of the main body of the tool 2 is a stem 8, and the upper endof said stem is drilled and threaded to receive the lower screw threaded end I0 of the handle structure. This end piece l0 forms a part of a shaft II which extends through the hand piece or grip portion l2 of the handle and has a slip connection at its upper end with the lower end piece l3 of the internal revolving element M of the flexible shaft. Ball bearings are interposed between the shaft II and the shell or hand piece I2 so that the former can revolve freely inside the latter, and the hand piece is fastened to the usual terminal fitting l5 of the flexible armor in which the element I4 rotates. Handle structures of this character are known and no novelty is claimed in this particular arrangement.

At the upper end of the flexible shaft the end piece I6 is connected to the motor casing or housing l1, and the terminal member 18 of the rotary element of the shaft is of approximately a square section and projects into 9. correspondingly shaped hole 20, Figs. 5 and 6, in the clutch 5. This clutch structure includes a driving element 2| which is pinned to the motor shaft 22, a driven member 23, and a friction element 24 between the parts 2| and 23. The end piece 21, in which the hole 20 is formed, is secured rigidly to the part 23. A spring 25 which encircles the sleeve portion of the driven element 2i and is backed up by a nut 23 threaded on said sleeve portion, serves to press the abutting surfaces of the parts 2|, 23, and 24 together and thus, in connection with the characteristics of these abutting surfaces, determines the degree of friction exerted by the clutch. By adjusting the nut 26, or changing the spring 25, this degree of friction may be varied and predetermined.

For most capping operations it is preferred to use a high speed motor of very small horse power, say for example, in the neighborhood of one-sixth or one-eighth horse power, and to so adjust the friction of the clutch 5 that the torque transmitted through this clutch to the tool 2 will be considerably less than that required to perform the cap tightening operation. In other words, the motor will not be depended upon to deliver the torque required for the final cap tightening operation, but instead, the effort required for this purpose will be supplied by kinetic energy stored in some convenient part rotating with the tool 2. Preferably this energy is supplied either by making the tool body itself of suitable mass, or more desirably, by mounting directly on it a series of welghtsin the form of washers 28. As shown in Figs. 1 and 2, these washers are slipped on the stem 3 of the tool and rest on the upper surface of the tool body, but they are held against said tool with sufllclent pressure to compel them to revolve with the tool, this pressure being applied by a nut 30.

With this arrangement the torque transmitted by the motor to the tool 2 need be only little more than that required to perform the earlier part of the operation of screwing up the cap, and, as above indicated, the effort required to tighten the cap is supplied by the kinetic energy of the mass rotating with the tool 8, this energy being delivered in the last fraction of a revolution of the cap.

In using the apparatus the revolving tool 2 is brought down upon the top of the cap, the tapered surfaces of the rubber member 1 engaging the margin of the cap and revolving it in the proper direction to screw it up. As the cap begins to tighten, and consequently tends to reduce the speed of rotation of the tool, the kinetic energy of the weights is released and delivers the additional torque required to complete the cap tightening operation. when the cap can be turned no further, the tool stops and the clutch slips. Since the tool is operated at high speeds, say for example, 1600 or 1800 R. P. M., or possibly more, and

because of the instantaneous release of the stored up kinetic energy, the time required to apply an individual cap is extremely brief, say for example, only a second or thereabouts in a typical case. Also, because the kinetic energy is actually applied only during the last fraction of a turn in which the cap is being tightened and then is released, and since the clutch is adjusted with an exceedingly light tension, the twist transmitted to the container is minimized and is made only that absolutely necessary to tighten the cap, the torque or twist dying out completely with the-stopping of the tool. Consequently, much of the effort required to hold the container against the twist exerted by the tool is eliminated. Upon lifting the tool from the cap, it speeds up almost instantly.

By suitably predetermining the kinetic energy so delivered, the machine may be accurately addusted to the requirements of the cap tightening operations on different containers. Since the kinetic energy of a moving body varies directly with its mass and with the square of its velocity, such 5 tool 2 so that the number and weight of these 10 washers may be adJusted as required for different capping operations. For the same reason, also, the motor 4 may be made of the variable speed typ and its speed may be adjusted in any suitable manner as, for example, by the intro- 15 duction of a variable resistance 3| in the power supply line running to the motor. Also, instead of mounting the weights 28 in the manner illustrated in Figs. 1 and 2, the stem 8 of the tool body 2 may be provided with a spline or key 32, as shown in Figs. 3 and 4, the weights 28' having slots to receive the key, and the nut 30 of the construction previously described being omitted.

It will be evident that this arrangement greatly reduces the duty required of the motor 4 and the clutch I. Also, that the strain on the flexible shaft 3 is lessened very substantially. Consequently, this machine is freed of those factors which have been responsible for producing mechanical failure and a great deal of annoyance and interruption in service in prior machines. In addition, the efiort required to eifect the final tightening of the cap can be adjusted conveniently and accurately to the requirements of the particular cap and its container. It is contemplated that these improvements may be utilized in other machines for performing operations essentially like those of cap tightening and where the same general organization can be used.

Preferably a spring 33 is connected with the flexible shaft 3, as shown in Fig. 1, where it supports substantially the entire weight of the parts below it.

While I have herein shown and described a preferred embodiment of my invention, it will be understood that the invention may be embodied in other forms without departing from the spirit or scope thereof.

Having thus described my invention, what I desire to claim as new is:

1. In a machine for applying screw caps and thelike, the combination of a tool for operatively engaging a cap, a motor, a flexible shaft driven by said motor and connected with said tool to revolve it, a friction clutch between said shaft and motor adapted to slip under a relatively light load, and removable means located between the end of said shaft and the cap engaging surface of the tool to supply the greater part of the kinetic energy used in the final tightening of the cap.

2. In a machine for applying screw caps and the like, the combination of a tool for operatively engaging a cap, mechanism for rotating the said tool, and a series of weights removably mounted on said tool to revolve with it and operative to store kinetic energy available instantly to drive the tool when its rotary motion is reduced by the resistance of the work.

3. That improvement in methods of tightening screw caps and the like, which consists in utilizing a source of power to revolve the cap, limiting the torque transmitted to the tool by said source of power .to less than that required for the cap tightening operation, storing kinetic euergy in the parts revolving with said tool, utilizing said energy to produce a high percentage of the final cap tightening eilfort, and adjusting said efiort by suitably predetermining the kinetic energy so produced.

4. That improvement in methods of tightening screw caps and the like, which consists in utilizing a source of power to revolve the cap tightening tool, storing kinetic energy at said tool when the latter is not working, adjusting the energy so stored to such a value as to produce a final tightening efiort of approximately the desired intensity and of substantially greater value than that which the source of power alone is capable of delivering, and causing the driving connections between said source of power and the point at which said energy is stored to slip when the torque required by the work becomes excessive.

5. In a machine for applying screw caps and the like, the combination of a tool for operatively engaging a cap, a motor, a flexible shaft driven by said motor and connected with said tool to revolve it, a friction clutch between said shaft and motor adapted to slip under a relatively light load, and means removably mounted on said tool for storing kinetic energy when the tool runs freely and delivering to the tool the greater part of the kinetic energy used in the final tightening of the cap.

6. In a machine for applying screw caps and the like, the combination of a tool for operatively engaging a cap, said tool comprising a hollow body adapted to rotate about a vertical axis with the lower end of the tool open, and a bushing of yielding material in said open lower end, said bushing having a tapered surface to engage the cap, mechanism for rotating the said tool at a high speed to screw up the cap, and adjustable means revolving in unison with said tool and having suilicient mass to supply a high percentage of the kinetic energy used in the final tightening of the cap, the mass of said energy supplying means 20 being adjustable at the will oi! the operator.

EDWARD w. DONAHUE. 

